The present invention relates to a thermal transfer image forming material in which an image is transferred to an image receiving material employing thermal transfer, and particularly to a thermal transfer image forming material, preferably employing a light-to-heat conversion-type heat mode recording method in which light is converted to heat, and thermal transfer is carried out employing generated heat. The present invention is related to a light-to-heat conversion-type heat mode recording material which is more preferably capable of producing highly detailed and/or full color images employing digital dry process.
In light-to-heat conversion-type heat mode transfer, an image forming layer is transferred to an image receiving material from a recording material, and images are obtained by transferring the image forming layer to a final image recording material from the image receiving material. Therefore, close contact between the recording material and the image receiving material is extremely important. In particular, when an image is highly detailed, close contact depends greatly on the smoothness of the sheet of paper. Resolution in the range of a few to a dozen or so xcexcm is required even for a color proof, which reproduces halftone dots and the unevenness of the surface of each sheet of paper cannot be ignored.
Japanese Patent Publication Open to Public Inspection No. 6-22080 discloses that as a means to enhance the close contact between a recording material and an image receiving material, a flexible or thermally softenable cushion layer is provided between the support and the image forming layer or the image receiving layer. In this case, the same patent publication describes a structure in which the recording material comprises at least a support, a cushion layer, a light-to-heat converting layer, and an image forming layer, and the image receiving material comprises at least a support, a cushion layer, a peeling layer, and an image receiving layer. In this technique, an image is formed in such a manner that the image forming layer, which is subjected to imagewise exposure during light irradiation, is peeled from the surface of the light-to-heat converting layer and the resulting image is then transferred to the image receiving layer of the image receiving material. The transferred image is laminated onto a final support employing the subsequent process, and the peeling layer as well as the image receiving layer is peeled from the surface to form a final image.
However, in these conventional examples, uneven density occasionally results in an image area during image formation, which has been noted as a problem.
Japanese Patent Publication Open to Public Inspection No. 6-127685 discloses a method in which a composition prepared by dissolving flexible elements in a solvent is applied onto a support to form a cushion layer, and before winding the resulting coating, an intermediate layer (a light-to-heat converting layer or a peeling layer) is adhered and a recording material or an image receiving material is prepared by applying an image forming layer or image receiving layer onto the resulting coating. However, in the above-mentioned method, during coating of the image forming layer or image receiving layer, the coating solvent penetrates into the cushion layer, and problems have occurred so that the storage stability of material itself is degraded due to the residual solvent, and the surface properties of the image forming layer as well as the image receiving layer tend to deteriorate.
Hence, the present inventors applied for Japanese Patent Application No. 7-8994 proposing the production method of a light-to-heat conversion-type heat mode recording image forming material in which transfer can be carried out so that the intermediate layer and the image forming layer are subjected to no peeling between layers and further, the releasing layer is utilized which results in no decrease in melt transfer sensitivity. However, this method resulted in another problem in which the production cost is raised due to the use of a temporary support.
When, without using said temporary support, a cushion layer, an intermediate layer, and an image forming layer are provided on a support employing a coating method in which each layer is successively applied thereon, unevenness results on the cushion layer due to flaws which are caused by the fact that the cushion layer, as the lower layer, is flexible during coating of the upper layer. The resulting unevenness adversely affects the performance of a light-to-heat converting agent and the like, and problems such as coating streaks, coating mottles, flaws due to conveyance rollers, and the like have occurred.
Further, in the above-mentioned coating method, after coating the cushion layer onto the support, the resulting coating is occasionally wound and stored in roll form until coating of an intermediate layer or an image forming layer. In such a state, another problem has occurred in which the cushion layer adheres to the reverse surface of the support due to the flexibility of the cushion layer itself, making it difficult after unwinding to coat an intermediate layer or an image forming layer during a coating process.
In view of the foregoing, the present invention has been accomplished. A first object of the present invention is to provide a light-to-heat conversion-type heat mode recording material which comprises a flexible cushion layer and exhibits excellent close contact with an image receiving material. A second object of the present invention is to provide a heat mode recording material which does not results in coating streaks, coating mottles, generation of flaws due to conveyance rollers, winding defects, and makes it possible to perform image transfer without a decrease in sensitivity. A third object of the present invention is to improve close contact, as well as to improve image defects due to tent during image formation and thereby uneven density within the transferred surface.
Another object is to provide a heat mode recording material which is simpler and more enabling cost reduction than those prepared by employing a conventional coating method in which a temporary support is used.
The above-cited objects of the present invention are accomplished by the thermal transfer image forming materials described below.
A thermal transfer image forming material of the invention comprises a support, an intermediate layer and an image forming layer containing a colorant and a binder, wherein a part of the image forming layer transfers by thermal transfer and the intermediate layer contains a matting material.
A number average particle diameter of the matting material is preferably greater than the thickness of the intermediate layer.
A part of the matting material contained in the intermediate layer is preferably projected from the outermost surface of a thermal transfer image forming material.
The intermediate layer preferably containing a matting material is a cushion layer.
The cushion layer contains preferably matting material of 100 to 3,000 particles/mm2 and the difference between the number average particle diameter of the matting material and the thickness of the cushion layer is 1 to 5 xcexcm.
The cushion layer contains preferably matting material of 300 to 2,000 particles/mm2 and the difference between the number average particle diameter of the matting material and the thickness of the cushion layer is 1 to 3 xcexcm.
The elastic modulus of the cushion layer is preferably not more than 250 kg/mm2 at 25xc2x0 C.
The custion layer preferably contains a binder and glass transition temperature (Tg) of the binder is not more than 80xc2x0 C.
The penetration of the cushion layer is preferably at least 15 under the standard test conditions of JIS K2530-1976, an English translation of which is attached as an Appendix.
The thermal transfer image forming material comprises a cushion layer, and the intermediate layer containing the matting material is preferably a layer other than the cushion layer, preferably contains matting material of 100 to 3,000 particles/mm2 and the difference between the number average particle diameter of the matting material and the thickness of the cushion layer is 0.2 to 4.5 xcexcm.
The thermal transfer image forming material mentioned above in which the intermediate layer preferably contains matting material of 300 to 2,000 particles/mm2 and the difference between the number average particle diameter of the matting material and the thickness of the cushion layer is 0.5 to 3 xcexcm.
The thermal transfer image forming material mentioned above in which elastic modulus of the cushion layer is not more than 250 kg/mm2 at 25xc2x0 C.
The thermal transfer image forming material mentioned above in which, preferably, the cushion layer contains a binder and glass transition temperature (Tg) of the binder is not more than 80xc2x0 C.
The thermal transfer image forming material mentioned above in which the penetration of the cushion layer is preferably at least 15 under the standard test conditions of JIS K2530-1976.
The thermal transfer image forming material mentioned above in which wherein "sgr"/rn of the matting material is not more than 0.3; wherein "sgr" represents the standard deviation of the particle distribution of the matting material and rn represents number average particle diameter of the matting material.
The other embodiment of the invention is described.
A light-to-heat conversion-type heat mode recording material, which comprises successively a cushion layer and an image forming layer, in this order, provided on a support, wherein the cushion layer comprises a matting material having a number average particle diameter greater than the average thickness of the binder component of said cushion layer.
A light-to-heat conversion-type heat mode recording material which comprises a cushion layer, an intermediate layer, and an image forming layer provided on a support, wherein the intermediate layer comprises a matting material having a number average particle diameter greater than the average thickness of the binder component of said intermediate layer.